Ion measurements in the stratosphere and mesosphere with newly developed mass spectrometers
December 2, 2021
Ion measurements in the stratosphere and mesosphere with newly developed mass spectrometers
In September and October 2021, IPA conducted balloon and rocket measurements in northern Scandinavia to study the ion composition in the stratosphere and mesosphere. The composition and chemistry of ions in the middle atmosphere (10-100 km) is very complex and so far, only incompletely known. During the two measurement flights, two new quadrupole mass spectrometers built at IPA were used. These are operated with a neon cryopump to generate the necessary vacuum for the measurement.
The research focus of the rocket instrument was on the analysis of very heavy ions produced in connection with the ablation of meteorites in the mesosphere, so-called meteor smoke particles. These play a role in the context of polar mesospheric winter echoes (PMWE), which were studied during the rocket campaign.
The balloon flight focused on cluster ions in the stratosphere and included an investigation of how the La Soufriere volcano, which erupted in April, affected the climatologically important stratospheric aerosol layer.
Credit:
Figure 1: Sounding rockets of the PMWE measurement campaign at the Andøya Space site. ROMARA is mounted on the upper deck of the left rocket. DLR / MORABA / J. Keller (CC BY-ND-NC 3.0).
The ROMARA rocket mass spectrometer was launched from the Norwegian island of Andøya around noon on October 1, 2021, as part of the 2nd part of the PMWE measurement campaign of the Institute of Atmospheric Physics from Kühlungsborn, Germany. Compared to the original version from the successful first flight in spring 2018, the instrument was significantly improved: altitude resolution, mass range and reduced cross-sensitivities during flight. The payload reached an altitude of about 125 km. A first data review shows that the measurement flight was very successful. A wide variety of molecular and cluster ions of both polarities as well as heavy, negatively charged particles with up to about m/z = 6000 could be measured.
The balloon flight took place within the framework of the EU project HEMERA (H2020 V2) from the launch site of the ESRANGE Space Center in northern Sweden. The new IPA balloon mass spectrometer BAMARA includes several technical innovations. Among others, an extensive pumping system was integrated, consisting of an additional turbomolecular pump together with a backing pump to support the cryopump. The first flight of the IPA balloon mass spectrometer (Fig. 2) took place on September 11, 2021. During the ascent, ion measurements were obtained at 25 km altitude, the expected altitude range of the La Soufriere volcanic cloud. Initial analyses of the mass spectra show a high fraction of cluster ions containing sulfuric acid. This indicates that the volcano injected large amounts of SO2 into the stratosphere. This results in elevated sulfuric acid concentrations that react with the ions.
Credit:
Figure 2: Maiden flight of the IPA balloon mass spectrometer on September 11, 2021 in northern Sweden. DLR / H. Schlager, (CC BY-ND-NC 3.0).
Both instruments were recovered virtually undamaged after their flights, allowing them to be deployed again with minimal effort.
